1. Technical Field
The present invention relates to power supplies in general, and in particular to a method for controlling output power of an AC/DC adapter and power consumption of a load within a notebook type portable computer.
2. Description of Related Art
A notebook type portable computer (notebook PC) has a relatively simple system configuration when being used in a mobile environment in order to prolong battery-powered operating time. On the other hand, when being used in an office environment, the notebook PC can be connected to a function extending apparatus known as a docking station or a port replicator so that a user can utilize the features and capabilities corresponding to a desktop computer. The notebook PC is generally equipped with a charger, and in some cases, a special charger is also mounted on the function extending apparatus.
When the notebook PC is used in a state of being connected to a function extending apparatus, an AC/DC adapter is not connected directly to the notebook PC but the AC/DC adapter preliminarily connected to the function extending apparatus supplies power to a system load of the notebook PC, a charger of the notebook PC, a system load of the function extending apparatus, and a charger of the function extending apparatus. Among the system load, a central processing unit (CPU) exhibits the largest maximum power consumption. The AC/DC adapter has rated power suitable for the maximum power consumption of the entire of the system load including the CPU. The variation in the power consumption of the system load is severe, and charging the battery by means of the charger is not always an urgent task. Therefore, when the rated power of the AC/DC adapter is set to be larger than the sum of the total maximum power consumption of the system load and the maximum power consumption of the charger, the utilization rate of the AC/DC adapter may decrease, and thus, the battery is overcharged.
Therefore, the charging of a battery by means of a charger is generally carried out by using surplus power that is a difference between the rated power of the AC/DC adapter and the power consumption of the system load. In this case, when the notebook PC is used in a state of being connected to the function extending apparatus, power is supplied from the AC/DC adapter connected to the function extending apparatus, to the system load of the notebook PC, the system load of the function extending apparatus, the charger of the notebook PC, and the system load of the function extending apparatus. However, depending on the overall power consumption or the output power of the AC/DC adapter, it may be necessary to limit the power consumption of any of the loads.
Generally, in a notebook PC that does not limit the power consumption of a system load, the power consumption of either the charger of the notebook PC or the charger of the function extending apparatus (or both chargers) can be limited when the power consumption of the system load increases. One method to control the power consumption of either one or both of the chargers can be based on the measurement results of the power consumption of the charger of the notebook PC and the power consumption of the charger of the function extending apparatus. Specifically, a configuration may be considered in which when output power of an AC/DC adapter exceeds a predetermined value, the power consumption of the charger of the notebook PC is compared with the power consumption of the charger of the function extending apparatus so that the larger power consumption is limited.
However, with such a method, in order to limit the power consumption of the charger of the notebook PC or the charger of the function extending apparatus, it is necessary to acquire information regarding the power consumption of both chargers. The AC/DC adapter needs to supply power to the function extending apparatus connected to the notebook PC or the function extending apparatus not connected to the notebook PC. Therefore, when the notebook PC is not connected to the function extending apparatus, it is impossible to acquire information of the charger of the notebook PC, and thus, it is difficult to employ the above-mentioned method.
Consequently, it would be desirable to provide an improved method for controlling output power of an AC/DC adapter and power consumption of a load within a notebook PC.